Accession Number : ADA119182

Title :   Dynamic Fracture Behavior of Structural Materials.

Descriptive Note : Annual rept. no. 1, Feb 81-Feb 82,


Personal Author(s) : Shockey,D A ; Giovanola,J H

PDF Url : ADA119182

Report Date : Mar 1982

Pagination or Media Count : 16

Abstract : The goals of this research program are first to develop and apply procedures for obtaining more accurate measures of dynamic fracture initiation and propagation toughness, and then to establish the relationship between them. The dynamic initiation toughness K sub Id will be obtained by applying short pulse loads to SEN specimens and using minimum-time crack instability criteria. The dynamic propagation toughness K sub Id will be obtained by measuring the temperature histories in material near the tip of a fast running crack. During the first research year, a Charpy impact machine was modified to produce a well-defined tensile pulse in a SEN specimen. Flat-topped pulses of a shape suitable for K sub Id determinations were obtained that had rise times of about 18 microseconds and durations of 50 microseconds and 100 microseconds. A high-spatial-resolution temperature measuring instrument, based on laser thermoprobe concepts, was constructed and evaluated for use in K sub ID determinations for fast running cracks. By monitoring the change in intensity of a monochromatic light beam passing through a thin CdS film, we could measure the temperature of the film substrate to 0.25 cover a range of 150 C. Thus the technique appears suitable for dynamic fracture investigations.

Descriptors :   *Alloys, *Crack propagation, *Fatigue(Mechanics), *Charpy impact tests, Dynamic loads, Toughness, Stability, Cadmium compounds, Cadmium sulfides, Construction materials, Thin films, Substrates, Tensile properties, Temperature, Light pulses, Lasers, Fracture(mechanics)

Subject Categories : Metallurgy and Metallography
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE